Blood Sugar Monitors

Dexcom's Stelo CGM

In the past, people with diabetes have monitored their blood sugars through many forms of testing modalities. Having blood drawn at the doctor’s office is the easiest for many where their blood sugars and/or hemoglobin A1C readings are measured with no effort of their own. Then there’s the hand-held, portable glucose meters (glucometers) where you prick your finger for blood and insert a test strip in the meter for an immediate reading. Some people can do the latter up to six times a a day. After a while, your fingers do hurt! Now, there’s a new guy in town—the CGM.

Continuous glucose monitors (CGMs) are the latest in glucose sensor technology. CGMs are wearable, 24/7 devices that use a small sensor inserted under the skin to measure glucose levels in the interstitial fluid; that’s the fluid around your cells just beneath the skin, rather than directly in a blood vessel. We know that glucose (the sugar that comes from foods we eat) hits the bloodstream first, but it can leak into the surrounding interstitial fluid. What I have learned in my research is there’s a lag time between blood glucose levels and interstitial glucose levels, which means there may be a few minutes delay in a CGM sensor reading compared with a glucometer reading. Fingerstick checks can act as a backup tool to confirm CGM results. There is also a 15% margin of error for the CGM; especially important for those on insulin.

CGMs are often covered by health insurance if you meet certain criteria. For most health insurance plans that means you need to be on insulin; diagnosed as Type 1 or insulin-dependent Type 2 diabetes. I am not 100% sure if this has changed. If a CGM is deemed as “medically necessary” they may be covered with a pre-authorization. I encourage patients to check with their own insurance companies. Most recently, over the counter (OTC) CGMs have entered the marketplace. They are Dexcom’s Stelo and FreeStyle’s Libre. I can't speak to the cost of the Libre but when I met with a vendor representative for Stelo, I was quoted their OTC version costs $89-$99 for a one month coverage (cost depends on if you opt for a subscription plan). You get two sensors; each one lasts for 15.5 days. You affix the sensor on the back of your arm. All CGM systems use a transmitter to wirelessly send the glucose data from the sensor to a device where you can view it, so you need to download an app that connects with the sensor; it reads out a blood sugar reading every 15 minutes.

I had an opportunity to try the Dexcom Stelo at no cost to me. I had the meter for three months but I delayed opening the box. Then one day, I met with a patient of mine who shared his CGM app results with me and I was intrigued. I wanted to know how these monitors felt and how they worked. It was on my arm by end of day!

I always wondered if my blood sugar ran low at times. I’d get that foggy brain, hangry feeling if I didn’t eat on time. While I didn’t notice any abnormal lows in my sugars, I noticed 50 point drops about 30 minutes after the highest peak. I’m thinking my insulin is still cranking and working efficiently. Yay!

After seven days I took off the sensor; yes, eight days early. Actually, I had to pry it off! It was pretty well stuck to my arm. I could see the welts it made on my skin after I removed it. I definitely had a reaction to the adhesive. I was curious as to what probe entered my arm—it looked like a very fine electrode. 

So, by now you were wondering what my take is on these monitors. The pros for me include increasing a patient’s engagement and knowledge base in the self care and management of their diabetes. The monitors are able to give you a birds eye view how daily food, activity, illness, and stress can influence blood sugar numbers. They alert you to the highs and lows and allow you the opportunity to treat blood sugar reactions before they ensue. They also reduce the number of times you have to stick your finger or carry around a glucometer and strips. You do need your phone handy though. 

The adhesive issue was a big con for me. It was painful to remove. I also felt like I had something tugging on my arm for the week. Not an ache. Just a dull heaviness. It’s also pretty obvious in summer clothing. Plus, I had an issue with it while sleeping on my side. It seemed in the way. But the number one concern I had was that I was becoming too obsessed with the numbers. I checked it too often—all day long. I kind of felt like I was back in my A & P lab at college; recording my findings of my mouse experiment. And so, I removed it on Day 7 as I had all the data I needed.

Talk to your primary care or registered dietitian if you think you are a good candidate for a CGM. Take control of your blood sugar and your health—it all starts with one tiny pinch!

In Good Health, 

Sophie